Psicrystals are great. Familiars, not so much.
Since psicrystals are constructs, they don't have to eat, breathe, or sleep. They're immune to poison, can see in the dark, have decent perception skills, and are perfectly capable of being sneaky (they're Diminutive, yo!). They can be metamorphosis'd into golems. They work well for taking your spot during a watch, for long-range recon (1 mile telepathy!), as universal translators, and for keeping the party scout within communications range.
They're incredibly versatile li'l buggers, and can be used offensively what with the Share Powers and Channel Powers abilities (they can make touch attacks for you with Medium BAB and size bonuses - they get HD-based feats, so that Str penalty can be replaced with the Dex bonus). They can also Aid Another to boost your skill checks, and (RAW, at least) can UPD for you.
They're also good infiltrators; just fluff them to look like precious gems, and what band of thieves wouldn't want to take it home with them?